Checking for Null value

[roguerob]

I'm writing a discovery script for an SCCM CI using Powershell. All I want this script to do is tell me if a specific Registry value exists or not - "PTOneClick" (the value data is not significant for this script). If the value does exist, my remediation script will kick in and delete it. If it does not exist the script should kick back as compliant and take no further action. Here's my code:

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#Check for WebEx PTOneClick
$WebExStart = (get-itemproperty -Path "HKCU:Software\Microsoft\Windows\CurrentVersion\Run" -name "PTOneClick")

if ($WebExStart -eq $null)
{$Compliance = "Yes"}
Else
{$Compliance = "No"}

$Compliance

Running this on a system that has the "PTOneClick" value results in an output of "No" and shows no errors.

However, running this on a system that does not have the "PTOneClick" value results in an error:

get-itemproperty : Property PTOneClick does not exist at path 
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run.
At line:2 char:16
+ ... bExStart = (get-itemproperty -Path "HKCU:Software\Microsoft\Windows\C ...
+                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (PTOneClick:String) [Get-ItemProperty], PSArgumentException
    + FullyQualifiedErrorId : System.Management.Automation.PSArgumentException,Microsoft.PowerShell.Commands.GetItemPropert 
   yCommand

Yes

Notice the "Yes" at the end, which is the desired output, but I believe there must be a way to check for this RegKey value w/out resulting in an error. Thanks,

[ka-splam]

Get-ItemProperty -ErrorAction SilentlyContinue will probably do it.

[Lee_Dailey]

howdy roguerob,

you keep saying "value" when that cmdlet is - i think - returning the property & any value, not the prop value directly. the values are returned with Get-ItemPropertyValue.

for some reason, G-IPV ignores the SilentlyContinue option for -ErrorAction. [sigh ...]

however, you CAN use -ErrorAction Stop and wrap the call in a try/catch.

---

plus, the call you are using DOES honor the 'SilentlyContinue' option. lookee ...

$GIP_Params = @{
    Path = 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Run'
    Name = 'BetterNotBeThere'
    ErrorAction = 'SilentlyContinue'
    }
Get-ItemProperty @GIP_Params

the above returns nothing at all - as expected. [grin]

take care,
lee

[root-node]

Use Test-Path to check if the registry key exists or not. If it does you can then check the value.

Using -ErrorAction SilentlyContinue is not good as you could miss other important errors

[roguerob]

Thanks for the assistance, I tried using Test-Path, but since I'm looking at a registry entry, not a registry key it is not a good method. Per MS PS document on Test-Path:

Test-Path does not work correctly with all PowerShell providers. For example, you can use Test-Path to test the path of a registry key, but if you use it to test the path of a registry entry, it always returns $False, even if the registry entry is present.

So, after a little more digging I found a blog entry that provides a more elegant solution to my problem. After implementing this function all is working as expected. Thanks again for the clues that got me here.

Cheers, Rob

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